PREVIOUS BROADWAY BRIDGES: During the early 1890's, the dredging of the Harlem River Ship Canal, which for the first time created a navigable waterway between the East River and the Hudson River, necessitated construction of a new Broadway crossing between Inwood and Marble Hill. Alfred P. Boller, who engineering other movable crossings along the Harlem River, designed the original Broadway Bridge, or "Ship Canal Bridge."

The new bridge, which opened on January 1, 1895, was a single-deck steel swing span that imitated the design of the Madison Avenue Bridge. It replaced a temporary timber structure that was built during construction of the Ship Canal, and earlier, a ferry service that had run uninterrupted since 1693. The first permanent bridge was 26 feet above mean high water in the closed position, and running on steam power, opened and closed within three minutes. Warren trusses constructed above the deck flanked the main swing span.

Although the bridge met all the regulations set by the Army Corps of Engineers, it soon proved inadequate. By the turn of the century, the elevated IRT subway line had reached West 215th Street, about five blocks south of the Broadway Bridge. The New York City Department of Bridges determined that the existing structure would not be able to handle an extension of the IRT subway along the bridge, and ordered design work to begin on a replacement span.

The second permanent Broadway Bridge was completed on June 17, 1905. Designed as a dual-deck steel swing span, the 1,600-ton bridge had a 266-foot-long swing span that accommodated a 35-foot-wide roadway and two sidewalks on its lower deck, and three subway tracks (carried within three sets of dual beams) on its upper deck. In the closed position, the bridge had 25 feet of vertical clearance and 100 feet of horizontal clearance. Like the original bridge, Warren trusses flanked the main swing span.

THE NEW BROADWAY BRIDGE: During the late 1950's, the city decided to replace the existing span with a new, stronger Broadway Bridge. The 2,500-ton span more than doubled roadway capacity and added another subway track across the Harlem River. The lower deck supports two 34-foot wide roadways for vehicular traffic and two 8-foot wide sidewalks, while the upper deck supports three elevated tracks for the IRT #1 and #9 subway lines. For water traffic, the bridge has a navigable channel 304 feet wide, more than triple the width of the navigable channels of the old bridge. In the open position, the bridge has a vertical clearance of 136 feet.

The structural steel lift span of the bridge is suspended at each corner by two sets of wire ropes. Each set contains 12 ropes that are draped over a main counterweight sheave located on top of the corresponding corner of a tower. The other ends of the wire ropes are connected to span counterweights. Two electrical drives - one in each tower - raise and lower the lift span. The bridge also features four buffer cylinders mounted beneath the lift span - one in each corner - to cushion the shock of the lift span as it approaches either the open or closed position. To counter the engineering axiom that lift spans were ugly, the tops of the steel towers were tapered so that they would be flush with the main span when it was lifted.

The last train passed over the old Broadway Bridge on December 23, 1960, the day before the old span was floated down to the Bronx to be cut up into scrap. The new double-deck lift span, when had been assembled off-site, was floated onsite and hoisted into position two days later, on Christmas Day. The bridge opened the next day, but only for subway traffic.

More on the early days of the new Broadway Bridge by nycroads.com contributor Joel Gultz:

The #1 train ran two shuttles on The Bronx side using only the downtown track. One six-car R29 train would leave West 242nd Street and proceed to West 225th Street. It would pull in to the station as far away from the bridge as it could. It would wrong-rail north to West 242nd Street, and then the next train would do the same.It took another 18 months to fully open the bridge for vehicular traffic to allow workers to complete the towers, finish painting the bridge, and test the lift span. The bridge opened to vehicular traffic on July 1, 1962. During the fall of 1964, the lift bridge was raised for the first time in normal operation.

The Broadway Bridge - now in its third incarnation - carries approximately 40,000 vehicles per day (AADT) as part of US 9. To the south, the bridge connects to the Inwood section of Manhattan. To the north, the bridge connects to Marble Hill (geographically part of the Bronx, but politically part of Manhattan) and the Kingsbridge section of the Bronx.

REBUILDING THE BROADWAY BRIDGE: In 2003, the NYCDOT completed a $10 million minor rehabilitation of the Broadway Bridge. This work included applying a protective coating to the steel components of the lift span, installing new expansion joints, sealing and waterproofing the deck, repairing concrete, and building a new median barrier. The city plans a three-year, $22 million major reconstruction of the bridge beginning in 2010.

This photo shows the dismantling and removal of the second Broadway Bridge span on December 24, 1960. After the old swing span was removed, the new lift span was hoisted immediately into position. (Photo by Kenneth Palter; supplied by William Palter.)

Type of bridge:Construction started:Opened to rail traffic:Opened to vehicular traffic:Length of main span:Total length of bridge and approaches:Width of bridge:Width of roadway:Number of traffic lanes:Number of subway tracks:Clearance over mean high water (closed position):Clearance over mean high water (open position):Steel used in structure:Cost of original structure:

SOURCES:The Bridges of New York by Sharon Reier, Quadrant Press (1977); "A Guide to Civil Engineering Projects in and Around New York City," American Society of Civil Engineers (1997); Modjeski and Masters; New York City Department of Transportation; New York State Department of Transportation; Hank Eisenstein; Joel Gultz; David Jackino; William Palter.